The (Emerging) Reality of Corynespora cassiicola : Insights from a - PowerPoint PPT Presentation

http://www.bitkisagligi.net G. Vallad (2011) http://www.bitkisagligi.net The (Emerging) Reality of Corynespora cassiicola : Insights from a literature review Abraham Fulmer M.S. Student afulmer@uga.edu University of Georgia Department of Plant Pathology Major Professor: Dr. Bob Kemerait

The Course of this Talk  Introduction to the Fungal Pathogen  The Rise of Corynespora cassiicola  Life Cycle: What’s known (or not)  Fungicide Resistance

An Introduction ~ Nomenclature ~  First described by Berk. & M.A. Curtis 1868 as Helminthosporium cassiicola  Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei 1950  Kingdom: Fungi Phylum: Ascomycota Subphylum: Pezizomycotina Class: Dothideomycetes Order: Pleosporales Family: Corynesporascaceae  Common name of disease: • Corynespora leaf spot • Target spot http://www.mycobank.org/MycoTaxo.aspx?Link=T&Rec=296024 Systematic Mycology and Microbiology Laboratory (USDA) http://nt.ars-grin.gov/fungaldatabases

Pathogen Morphology  Colony Morphology Grey, Black, Dark brown, Green, • Concentric rings •  Conidiophores Simple, erect, intermittently • branching and septate Enteroblastic conidiogenous cells • produce subhyaline conidia singly or in chains.  Conidia Qi, Y. X et al. 2009. Variable in size and shape • 4-17 pseudosepta • Range from 40-220 µm in length and • to 8-22 µm in width, straight to curved with rounded apex and truncate base Conspicuous thickened hilum • Olive L.S., Bain D.C., and Lefevbre C.L. 1945. Ellis, M. B., and Holiday, P. 1971. Corynespora cassiicola (Berk. & A leaf spot of cowpea and soybean caused by an www.invasive.org http://www.padil.gov.au undescribed species of Helminthosporium . Phytopathology Curt.) Wei. Commonwealth Mycological Institute Descriptions of Fungi and Bacteria No. 31, Sheet 303. 50, 263–6.

Host Range  C. cassiicola has wide host range - from tropical and subtropical countries • 530 plant species from 380 genera , including monocots, dicots, ferns, and one cycad • Includes saprotrophic and endotrophic isolates  Reported on diverse substrates: • plant leaves • stems • roots • nematode cysts • human skin Huang, H.-K . et al. - Taiwan Dixon, L. J. 2008. Dissertation. University Of Florida 1. Dixon, L. J., Schlub, R. L., Pernezny, K., and Datnoff, L. E. 2009. Host specialization and phylogenetic diversity of Corynespora cassiicola . Phytopathology 99:1015-1027. 2. Huang, H.-K., Liu, C.-E., Liou, J.-H., Hsiue, H.-C., Hsiao, C.-H., and Hsueh, P.-R. 2010. Subcutaneous infection caused by Corynespora cassiicola , a plant pathogen. Journal of Infection 60 (2):188-190.

Major Diseases Caused by Corynespora cassiicola  Rubber ( Hevea brasiliensis ) Corynespora Leaf Fall Disease • First epidemic to gain notoriety • Sri Lanka - 4600 ha of rubber clone • (RRIC 103) destroyed since 1987 Malaysia, Indonesia and Thailand • http://mvmtechnologies.info/main/index.php?id=164 Nghia et al., 2008. 1. Silva, W. P. K., Karunanayake, E. H., Wijesundera, R. L. C., and Priyanka, U. M. S. 2003. Genetic variation in Corynespora cassiicola : a possible relationship between host origin and virulence. Mycological Research 107 (5):567-571. 2. Fernando, T.H.P.S., Jayasinghe, C.K., Wijesundera, R.L.C. and Siriwardana, D. 2010. Screening of fungicides against Corynespora leaf fall disease of rubber under nursery conditions. Journal of Plant Diseases and Protection, 117 (3), 117–121

Other Epidemics of Note ≈ 30 years  Cucumber ( Cucumis sativus ) • Recently, corynespora leaf spot has become one of the most important diseases of cucumber. • 7- to 10-day intervals during the 4-5 month growing season  Tomato ( Lycopersicon esculentum ) www.invasive.org • Serious pathogen on winter grown tomatoes • Losses in marketable yield of 11 800 kg/ha Gary Vallad . UF, Gulf Coast REC 1. Miyamoto, T., Ishii, H., Stammler, G., Koch, A., Ogawara, T., Tomita, Y., Fountaine, J. M., Ushio, S., Seko, T., and Kobori, S. 2010. Distribution and molecular characterization of Corynespora cassiicola isolates resistant to boscalid. Plant Pathology 59 (5):873-881. 2. Pernezny K., Stoffella P., Collins, J., Carroll A., Beaney A. (2003): Control of target spot of tomato with fungicides, systemic acquired resistance activators, and a biocontrol agent. Plant Protect. Sci., 38 : 81–88.

The Rise of Corynespora cassiicola First Reports 2012= 5  Increasing awareness? for 2013 = 7  Or Corynespora cassiicola  Increasing aggressiveness / 16 dissemination of virulent # of Publications 14 isolates? 12  All of the above? 10 8 6 4  72 documented first reports 2 from 1957 – 2013 0 Google Scholar, APS • Journals, Australasian Plant Year of Publication Disease Notes 1. Miyamoto, T., Ishii, H., Stammler, G., Koch, A., Ogawara, T., Tomita, Y., Fountaine, J. M., Ushio, S., Seko, T., and Kobori, S. 2010. Distribution and molecular characterization of Corynespora cassiicola isolates resistant to boscalid. Plant Pathology 59 (5):873-881.

Increasing First Reports 1 Documented since 2005 1. Shimomoto, Y., Sato, T., Hojo, H., Morita, Y., Takeuchi, S., Mizumoto, H., Kiba, A., and Hikichi, Y. 2011. Pathogenic and genetic variation among isolates of Corynespora cassiicola in Japan. Plant Pathology 60 (2):253-260. 2. http://apsjournals.apsnet.org 3. http://www.publish.csiro.au/index.cfm

2011 - Proof of Target Spot Koch’s Postulates  100% of inoculated plants showed symptoms  No symptoms found on non-inoculated plants  Fungus was re-isolated, cultured, and confirmed by morphological characteristics and PCR  Symptoms associated with this disease

Life Cycle of Corynespora cassiicola The Evolution of An Educated Guess

A Typical Life Cycle Scenario Prediction: Anticipating the Behavior

Development of Disease? Factors involved in Predicting Disease Severity  How does it overwinter? How long can it survive?  What’s the effect of tillage and crop rotation?  When does the pathogen emerge/start sporulating?  Secondary inoculum?  What is the relationship between environment and infection, etc?  When does infection begin?  Based on phenology, weather, planting date, etc?  All of the above?

Epidemiology Optimum Environment Host Temperature Leaf Wetness Tomato 20-28ºC (68-82.4) > 16 hours necessary Cucumber 25-30ºC (77-86ºF) - Tobacco 27.5-30ºC (81.5-86ºF) - Rubber 25-30ºC (77-86ºF) Greatest at 90% Cotton ? ? Mild Temperatures Prolonged Leaf Wetness - But to what extent?

A Hopeful Demise? Suppression with Fungicides  Fungicide Dependence • Cucumbers • Tomatoes • Papaya • Rubber –  Resistance is a major concern Rubber Institute of Sri Lanka • Strobilurins (QoI) • Boscalid (SDHI)

Cucumber Fungicide Trial Japan www.forestryimages.org www.forestryimages.org  Corynespora leaf spot • Now 3 rd most important disease in cucumber • Increasing severity in greenhouse production  Fungicide resistance • Already high frequency of resistance to: • Benzimidazoles • Strobilurin (QoI) ~ 6 years – Miyamoto et al. (2009) – DNA analysis suggests that resistant isolates were present before the introduction of QoI fungicides • Boscalid - succinate dehydrogenase inhibitor (SDHI) • Japan: Registered in 2006 (very effective control) • Wide spread Resistance reported in 2009 Miyamoto, T., Ishii, H., Seko, T., Kobori, S., and Tomita, Y. 2009. Occurrence of Corynespora cassiicola isolates resistant to boscalid on cucumber in Ibaraki Prefecture, Japan. Plant Pathology 58 (6):1144-1151.

Target Spot of Tomato Florida  Target Spot • Most serious disease of winter grown crop • Historically controlled with Bravo  Fungicide resistance • QoI – First documented in 2001 Gary Vallad . UF, Gulf Coast REC Miyamoto, T., Ishii, H., Seko, T., Kobori, S., and Tomita, Y. 2009. Occurrence of Corynespora cassiicola isolates resistant to boscalid on cucumber in Ibaraki Prefecture, Japan. Plant Pathology 58 (6):1144-1151.

Hypervirulence Gary Vallad. 2011. Initial Characterization of Corynespora cassiicola Affecting Florida Tomatoes. University of Florida, Gulf Coast REC.

Fungicides Labeled in Cotton  Currently – strobilurin chemistries are primary MOA labeled for cotton: • Headline • Quadris All Strobilurins • Twinline • Metconazole Photo: Courtesy Dr. Bob Kemerait & J. Brock

The Path Ahead Target Spot of Cotton  Emergence Awareness or Aggressiveness •  Epidemiology Knowledge gap Or • Inability to accurately predict • development How can we better predict the • behavior of target spot based on the life cycle?  Fungicide Resistance High Risk pathogen • 3-6 years of use for QoI and SDHI •

Questions? afulmer@uga.edu “It is hoped that this research will aid others in unraveling the many complexities that remain to be discovered with respect to C. cassiicola and its associated diseases.” Dixon et al., 2009